This article considers the potential benefits of integrating the knowledge base on adult learning with teacher inquiry. The first part of the article provides an overview of key concepts discussed in the literature on adult learning, including the characteristics of adult learners, self-directed learning, experiential learning, transformative learning, and adult learning in groups. The next part of the article focuses specifically on collaborative inquiry as adult learning, reviewing the purposes, principles, process, and facilitation of such inquiry found in the knowledge base on adult learning. The third part of the article reviews the literature on successful teacher inquiry and describes how such inquiry reflects the general knowledge base on adult learning. Next, the article describes how successful "collaborative" teacher inquiry is consistent with the literature on adult collaborative inquiry. The last part of the article reviews benefits of teacher inquiry consistent with the knowledge base on adult learning.